Sounds like the tensioner failed and allowed the chain to jump on the crankshaft.

Take the valve cover off and inspect the visible part of the chain. It's not broken or you wouldn't be able to get it started.

The problem may be obvious, may not. At any rate, check condition of rails, get a new tensioner, and turn engine to align the mark on the cam with the mark on the front cam tower. This is not very precise, but if you then look at the crank pulley you should be able to tell how far out the timing is -- more than 8 degrees is trouble. I suspect you will find more than that if the chain jumped.

If you are more than a tooth off, the cam towers will be broken from valve to piston interference.

Pull a new chain through, then re-set injection timing and cam timing.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!